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TX_Engineer, BSEE
Category: Consumer Electronics
Satisfied Customers: 515
Experience:  BSEE, years of electronics experience, board level repairs, analog and digital circuit experience
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The backup battery system on my home burglar alarm does not

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The backup battery system on my home burglar alarm does not function properly. Alarm is an Ademco 4152, installed in 1989, sold by Ackerman, and monitored by ADT. Malfunctioning symptoms include intermittent blinking in the "power" light when battery is connected, and battery overheating. Replaced battery on 10/08/10, no change. Consulted ADT via phone and replaced battery again on 10/26/10, no improvement. ADT said leave battery in for 24 hours to fully recharge. Same malfunctioning results. Alarm system works perfectly with standby system disconnected. Can you help? Ed
Hi, Ed..
Welcome back to JustAnswer.

You can take my answer for what it's worth, because I'm unable to give you circuit level troubleshooting for a 1989 Ademco alarm.. But I don't think anyone will be able to.

To determine what exactly is going on with the alarm, you'd need a volt meter.

Assuming your battery is initially charged, or establishes a full charge, it sounds like your alarm system is attempting to over charge it.

I fully charged battery will be 12.3 - 12.7v (when disconnected from the alarm/charger).

A battery under charge will be 12.7-14.4 (when connected to the alarm).

The charger on the alarm should "float" - that is, it should turn off when the battery doesn't need a charge. The fact that the battery is getting hot is indicating that it's taking an over charge and this condition is dangerous because it can cause a fire under some circumstances. The more the battery is over charged, the more likely it is to leak, fail, or cause a fire through some combination of leaking and ignition.

We could certainly get you a means to charge that battery with a good floating charger, but that's not going to help as your alarm system seems to indicate that it's pushing charge the entire time.

The fact that the power light is going on or off also indicates an internal circuit failure - perhaps too much current draw somewhere.

Short answer: Alarm is internally defective at this point. You should keep that backup battery removed (yes, I know in some systems this means that there will be an *annoying* reminder alarm) if it's over charging.

If you have a volt meter, we can confirm, but based on symptoms, I'd be shocked if I was wrong.

Replacing the internal circuits on a 1989 alarm is not a realistic option. The good news is that most of the alarm implementation / install is in the magnetic triggers / sensors that are already in your house and in most cases, those haven't change a whole lot in 20 years. Basically, I'm suggesting that you replace it.
Customer: replied 6 years ago.
Replacing the internal circuits is not an realistic option? Are you suggesting I replace something else? All the hardware and everything else is working properly.
Without significant diagnostic experience - meaning at least a digital volt meter and probably more realistically and oscilloscope, getting accurate board level repair advice is going to be very hard to find. I stress the word "accurate".

Using a volt meter, I can at least confirm that your unit is over charging or over discharging. Is testing voltage something you can do?

A circuit level repair might be a realistic option if there is a service manual available for a 1989 era alarm system, but I don't think you're going to find one.

A circuit level repair might be possible if we could identify damaged components - can you post a photo of the circuit board itself? Do you see anything scorched or damaged? Even then, replacing the electronic component does not guarantee success. Capacitors and things can leak after 20 years - anything damaging the board(s) themselves mean you have a paperweight.

We mass produce things these days - this produces a cost advantage for the consumer, but it also means that we usually replace rather than repair, for most items of "reasonable" replacement cost. Because this item is more than 20 years old, it will be very hard - if not impossible to find someone to repair it.

I'm suggesting if you have to replace - you're going to be replacing the alarm itself, IE the "brains" of the system. It's installing all of the sensors and switches that is so hard and expensive - in your case, I think that replacing the alarm itself, retaining all of the existing trigger hardware is the most viable and perhaps most economical option.

If you're not happy with the advice I'm giving you, feel free to opt me out and another expert will respond if he/she thinks differently.... Or relist the question.. I don't think you'll get a different answer, but I take no offense in having you try.. If you decide that I gave you good advice, you can always come back and accept this answer.

Sorry it's not the answer you want.. I wish I had better news for you.

Edited by TX_Engineer on 10/29/2010 at 1:43 AM EST
Note Ademco is now owned by Honeywell.

For people with a 4152 requiring service/replacement, I've seen the Ademco (Honeywell) Vista-20p recommended as the replacement:
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